Balloon catheter with stent and method for manufacturing it

ABSTRACT

The invention relates to a balloon catheter comprising a catheter tube, an inflatable balloon, the ends of which are attached to the catheter tube, and a stent attached around the balloon. The stent extends at least partly along the length of the balloon. In an uninflated state, at least the outside surface of the balloon not covered by the stent is provided with a relief structure which is substantially disappeared in an inflated state of the balloon. The invention also relates to a method for manufacturing such a balloon catheter.

This application is a continuation of Ser. No. 11/555,466, which is adivisional of Ser. No. 10/140,479, the disclosures of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a balloon catheter comprising acatheter tube, an inflatable balloon which at its ends is attached tothe catheter tube and a stent attached around the balloon, wherein thestent extends at least in part along the length of the balloon. Theinvention further relates to a method of manufacturing a ballooncatheter.

BACKGROUND INFORMATION

Balloon catheters of this type are generally known and are used fordilating vessels and lumina and for placing the stent in the dilatedvessel or lumen. In order to pass the balloon catheter easily and safelythrough the vessels and lumina and to position it at the required placefor dilatation, it is important that the balloon catheter has a smallprofile (outer diameter) and is sufficiently flexible.

The object of the invention is therefore to provide an improved ballooncatheter.

BRIEF SUMMARY OF THE INVENTION

The balloon catheter according to the invention is characterized inthat, in an uninflated state, at least the outside surface of theballoon that is not covered by the stent is provided with a reliefstructure which in an inflated state of the balloon is substantiallydisappeared.

Tests have shown that with a relief structure on the outside surface ofthe balloon a catheter is obtained that is more flexible than a standardballoon catheter. The balloon catheter according to the invention cantherefore be passed more easily and more safely through vessels andlumina to the point of dilatation. Because of its flexibility, thecatheter will be able to adapt better to a bend in a vessel or a lumen,thus reducing the risk of damage to the vessel or lumen.

The required relief structure may have different embodiments, butpreferably comprises at least one groove that extends at leasttransversely in the longitudinal direction of the balloon in order togive the catheter the required flexibility in a direction transverse tothe longitudinal direction thereof.

The groove preferably extends at a predetermined angle with respect tothe longitudinal direction of the balloon. According to a preferredembodiment, the groove extends helically from one end to the other endof the balloon, over the outside surface thereof.

According to another embodiment, the relief structure comprises two ormore grooves that extend helically from one end to the other end of theballoon, crossing each other. Tests have shown that with such a reliefstructure a very flexible balloon catheter is obtained which also has arelatively low profile.

The invention also relates to a method for producing a balloon cathetercomprising Attaching the ends of an inflatable balloon to a cathetertube and placing a stent around the balloon, whereby according to theinvention at least the outside surface of the balloon not covered by thestent is provided with a relief structure.

According to a first embodiment, the outside surface of the balloon isfirst provided with the relief structure and then the stent is attachedaround the balloon. An additional advantage of this embodiment is that abetter fixing of the stent to the balloon is achieved. The improvementin fixing is due to the relief that makes the usual smooth surface ofthe balloon “rough”. The stent adheres better to this rough surface.

According to a second embodiment, the stent is first attached around theballoon and then the outside surface is provided with the reliefstructure. A more flexible stent fixing system is obtained because atleast the balloon material near the stent, both distally and proximally,is provided with a profile. Also, the stent placing system has obtaineda smaller profile compared with known stent placing systems.

The relief structure is preferably produced on the application of heatto the surface of the balloon in order to deform the elastic material ofthe balloon.

The relief structure is also preferably produced on the surface of theballoon by applying a high pressure to the inside of the balloon.

According to a very inexpensive method, the relief structure is producedon the surface of the balloon by winding a wire around the balloon inthe form of a helix.

According to another simple method, the relief structure is produced onthe surface of the balloon by taking up the balloon in acounter-pressure body that has the relief structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail on the basis of the drawingsattached. The drawings show:

FIG. 1A is a side view of a form of a balloon catheter in an uninflatedstate,

FIG. 1B is a side view of the catheter in FIG. 1A in an inflated state,

FIG. 2A is a side view of a second embodiment of a balloon catheterduring the execution of the method according to the invention, and

FIG. 2B is a side view of the final product of FIG. 2A.

DETAILED DESCRIPTION OF THE INVENTION

A balloon catheter according to the invention comprises a catheter tube1, an inflatable balloon 2, which at its ends 3 is attached to thecatheter tube 1, and a stent 6 attached around the balloon 2. The stent6 extends partly along the length of the balloon 2 such that with thecatheter, both distally and proximally next to the stent 6, balloonmaterial lies freely. In an uninflated state (FIG. 1A), the outsidesurface of the balloon 2 has a relief structure 4 that in the inflatedstate has virtually or completely disappeared (FIG. 1B). The reliefstructure 4 gives the distal end of the catheter its requiredflexibility.

In the embodiments shown, the relief structure 4 consists of two grooves5, which extend helically from one end 3 to the other end 3 of theballoon 2 and cross each other. The uninflated balloon 2 has therebyobtained a padded relief surface. It is also possible to provide arelief structure with a single helically shaped groove 5 whereby theuninflated balloon 2 displays a relief surface in the form of a helix.Other relief structures are of course possible, provided that therelief, structure on the catheter creates the necessary flexibility in adirection transverse to the longitudinal direction of the balloon.

One way of obtaining the relief structure as shown in the drawings is bywinding a wire helically around the balloon 2. This wire may, forexample, be nylon wire or wire made of a different material thatcontracts somewhat on heating. After the wire has been wound around theballoon, a sleeve is pulled over the balloon. Subsequently, with theapplication of raised pressure to the inside of the balloon, the balloonis heated in such a way that in an uninflated state the balloon obtainsa relief structure that on dilating of the balloon at the dilatationsite in the vessel or lumen will virtually or completely disappear. Thesleeve is then removed and the balloon catheter can be inserted into avessel or lumen.

The method according to the invention can be carried out in two ways. Inthe first way, the profile is first applied to the balloon by windingthis around with wire and heating it under internal pressure, and thenthe stent is placed on the balloon. This results in improved flexibilityand maneuverability of the distal part of the catheter. Better fixing ofthe stent on the “rough”, profiled surface of the balloon is alsoachieved. In the second way, a stent is first placed on the balloon andthen the complete distal part of the catheter, namely the balloonincluding the stent that has been placed in position, is wound aroundwith wire, preferably nylon wire. Then the whole assembly is heated at acertain internal pressure. Winding produces a helical profile in theballoon material next to the stent. At the same time the diameter of thecatheter with the stent is reduced because the nylon wire shrinks onheating. In a variation of this last method, first filler material 8 isplaced next to the stent, over which wire is then also wound (see FIG.2A). In the end this results in a small increase 7 in the balloonmaterial next to the stent 6 (see FIG. 2B), into which the ends of thestent 6 can be pressed. As a result the ends of the stent 6 are betterprotected if the stent placing system is passed in a curved trajectory.

Instead of winding the wire, the balloon may be placed in a mould, whichis provided with the relief pattern required, in order for it to obtain,under raised pressure and temperature, the relief structure required.

Before the balloon is provided with its relief structure, preferably itis folded in the usual way in order to reduce its profile. By applyingthe relief structure, the profile will be reduced as an additional,advantageous effect.

Note that, although it is not shown in the drawings, it is possible toprovide the outside surface of the balloon with various helical groovesthat cross each other. In addition to helical grooves, grooves of othershapes are also possible.

The balloon catheter may be used not only in cardiological but alsoradiological interventions.

1. Method for producing a balloon catheter comprising attaching oppositeends of an inflatable balloon to a catheter tube, attaching a stentaround the balloon in an uninflated state, and providing at least theoutside surface of the balloon not covered by the stent with a reliefstructure which is substantially disappeared when the balloon is in aninflated state.
 2. Method according to claim 1, whereby first theoutside surface of the balloon is provided with the relief structure,and then the stent is attached around the balloon.
 3. Method accordingto claim 1, whereby first the stent is attached around the balloon, andthen the outside surface of the balloon is provided with the reliefstructure.
 4. Method according to claim 1, whereby before the outsidesurface of the balloon is provided with the relief structure, obliquelyto the stent, padding is applied over the balloon and the stent. 5.Method according to claim 1, whereby the relief structure is applied tothe surface of the balloon under the application of heat.
 6. Methodaccording to claim 1, whereby the relief structure is applied to theoutside surface of the balloon under the application of raised pressureto the inside of the balloon.
 7. Method according to claim 1, wherebythe relief structure is applied to the outside surface of the balloon bywinding a wire helically around the balloon.
 8. Method according toclaim 1, whereby the relief structure is applied to the surface of theballoon by taking up the balloon in a counter-pressure body providedwith the relief structure.
 9. Method for producing a balloon catheterfor use in combination with a stent, the method comprising: folding aballoon in an uninflated state in a manner which reduces a profile ofthe balloon; and forming at least one groove in an outside surface ofthe balloon including by winding a wire about at least a portion of theoutside surface of the folded balloon in a direction having a componenttransverse to a longitudinal axis of the balloon.
 10. Method accordingto claim 9, wherein the forming step further comprises: raising aninternal pressure of the balloon to a selected pressure; heating theresulting balloon structure; and removing the wire from the balloonwherein the at least one groove has been formed in the outer surface ofthe balloon.
 11. Method according to claim 9, wherein the wire is madeof a material which contracts when heated.
 12. Method according to claim9, wherein the material is nylon.
 13. Method according to claim 9,further comprising positioning the stent over the balloon prior towinding the wire about the balloon.
 14. Method according to claim 13,further comprising placing a filler material adjacent the ends of thestent prior to winding the wire about the balloon.
 15. Method accordingto claim 10, further comprising positioning the stent over the balloonafter heating the balloon structure.
 16. Method according to claim 9,wherein the forming step comprises forming a helical groove in theoutside surface of the balloon.
 17. Method for producing a ballooncatheter comprising providing an inflatable balloon attached at oppositeends to a catheter tube, providing the balloon in an uninflated statewith a stent and with at least the outside surface not covered by thestent including a relief structure, and causing the relief structure tosubstantially disappear when the balloon is in an inflated state. 18.Method according to claim 17, wherein the providing step comprisesproviding the relief structure from one end to the other end of theballoon.
 19. Method according to claim 17, wherein the providing stepcomprises providing the relief structure helically along the outsidesurface of the balloon.
 20. Balloon catheter comprising a catheter tube,an inflatable balloon having opposite ends and an outside surface, theends of the balloon being attached to the catheter tube, and a stentattached around the balloon, wherein the stent extends at least partlyalong the length of the balloon, characterized in that, in an uninflatedstate, at least the outside surface of the balloon not covered by thestent is provided with a relief structure, which is substantiallydisappeared in an inflated state of the balloon.